A flow volume detector of this type is disclosed in Patent Document 1. The flow volume detector disclosed in this document comprises a synthetic resin base which is attached to/detached from a flow volume measuring device. A pair of flow channels, in which a dialysate flows, is formed in the base. The base is provided with a detection terminal and an earth terminal in order to detect the flow volumes of the dialysates flowing in the respective flow channels.
One of the pair of flow channels is connected to an inflow route for conducting a dialysate into a dialyzer of an artificial dialysis apparatus in the state where the flow volume detector is attached to the flow volume measuring device. The other flow channel is connected to a return route for returning the dialysate from the dialyzer. The respective flow channels are arranged between a pair of magnetic poles of a magnetic circuit including an electromagnetic coil in the flow volume measuring device.
When the artificial dialysis apparatus is operated in this state, blood containing waste matter derived from a patient is introduced into the dialyzer and filtered. After transfer of the waste matter and moisture separated by filtration into the dialysate, clean blood after dialysis is returned to the patient again. At this time, electromotive forces, which are proportional to the flow rates of the dialysates flowing in the respective flow channels, are developed. The electromotive forces are detected by the respective detection terminals, and the flow volumes of the dialysates flowing in the respective flow channels are measured based on the flow rates of the dialysates and the sectional areas of the flow channels. Then, the amount of the waste matter separated from blood is calculated based on the difference between the flow volumes of the dialysates flowing in the respective flow channels.
According to the flow volume detector disclosed in this document, the pair of flow channels is formed adjacent to each other. Therefore, the base may be deformed if the temperature of a fluid flowing in one of the pair of flow channels becomes high. This is likely to cause a change in sectional area of the other of the pair of flow channels, resulting in the occurrence of an error in the measurement of the flow volume of the dialysate.